70 year-old nuclear reactor instructions revealed

Instructions on how to build a nuclear reactor have been revealed from five sealed envelopes that have lain hidden for almost 70 years.
The documents were sent to the UK's Royal Society for safekeeping by James Chadwick, discoverer of the neutron, during World War II.

He felt their contents, which described cutting-edge science, were far too sensitive to publish at the time. The envelopes were recently discovered in the science academy's archives.

They were opened on Thursday to mark the 75th anniversary of the neutron's discovery. The publication of James Chadwick's paper, The Existence of a Neutron, kick-started the field of nuclear physics.

Keith Moore, head of library and archives at the Royal Society, said: "The papers have only recently been discovered as part of our ongoing programme to catalogue the Society's archives.